Mid-afternoon on Friday, March 11, 2011, the earthquake hit.
Its epicenter was in the Pacific Ocean off northern Japan, and it caused a deadly tsunami (an unusually huge sea wave or series of waves caused by a quake or underwater volcanic eruption).
The Japanese tsunami wave was estimated to be taller than 23.5 m (77 ft.).
The tsunami drowned many people and swept away homes, cars and even planes at a nearby airport. More than 15 000 people died, with many thousands more injured or missing.
The earthquake damaged roads and railways, and fires destroyed many buildings. The disaster also affected nuclear power plants, releasing deadly radiation.
The effects of the earthquake were felt as far away as North America’s west coast. Since the disaster, Japan has experienced thousands of aftershocks, and these could continue for years.
After the disaster, radiation was found in food and water in Japan. That made people all over the world reconsider the safety of nuclear power.
The magnitude-9.0 earthquake was powerful enough to move Japan 4 m (13 ft.) closer to North America and shift Earth’s axis.
The speed of Earth’s rotation increased, which shortened the length of a day by 1.8 microseconds. Obviously, most people will never notice this, but it affects how spacecraft are navigated.